From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: "He, Junyan" <junyan.he@intel.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
Juan Quintela <quintela@redhat.com>, John Snow <jsnow@redhat.com>
Subject: Re: [Qemu-devel] Some question about savem/qcow2 incremental snapshot
Date: Wed, 10 Jan 2018 20:15:19 +0000 [thread overview]
Message-ID: <20180110201519.GF2451@work-vm> (raw)
In-Reply-To: <CAJSP0QVm+AoRoFNYx-r1k0WTPPopm60dmD7OhGZozm9ARfMwRQ@mail.gmail.com>
* Stefan Hajnoczi (stefanha@gmail.com) wrote:
> On Tue, Jan 9, 2018 at 7:55 PM, Dr. David Alan Gilbert
> <dgilbert@redhat.com> wrote:
> >> Certain guest operations like rebooting or zeroing memory will defeat
> >> the incremental guest RAM snapshot feature. It's worth thinking about
> >> these cases to make sure this feature would be worth it in real use
> >> cases.
> >
> > But those probably wouldn't upset an NVDimm?
>
> If the guest dirties all RAM then the incremental snapshot feature
> degrades to a full snapshot. I'm asking if there are common
> operations where that happens.
>
> I seem to remember Windows guests zero all pages on cold boot. Maybe
> that's not the case anymore.
>
> Worth checking before embarking on this feature because it could be a
> waste of effort if it turns out real-world guests dirty all memory in
> common cases.
Right, but I'm hoping that there's some magic somewhere where an NVDimm doesn't
get zero'd because of a cold boot since that would seem to make it
volatile.
Dave
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2018-01-10 20:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-25 7:54 [Qemu-devel] Some question about savem/qcow2 incremental snapshot He, Junyan
2018-01-09 15:35 ` Stefan Hajnoczi
2018-01-09 19:55 ` Dr. David Alan Gilbert
2018-01-10 19:16 ` Stefan Hajnoczi
2018-01-10 20:15 ` Dr. David Alan Gilbert [this message]
2018-01-10 20:17 ` Stefan Hajnoczi
2018-01-16 7:14 ` He Junyan
-- strict thread matches above, loose matches on Subject: below --
2017-12-25 7:33 He Junyan
2018-05-08 14:41 ` Eric Blake
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